The average new US home is about 2,600 square feet. You’ll get less than ten percent of that in these micro-apartments, which at their smallest are just 225 feet and make an art of fitting a life into a very sweet-looking closet.

The development of micro-housing—apartments and other dwellings smaller than 300 square feet—is a growing trend in many popular cities cramped for space. But where in the country can you find the teeniest examples of this trend? Maybe not the cities you'd first guess.

The 43-story De Rotterdam is Europe's largest building. Inside, however, it's a study in how to live inside a small space: The behemoth's tiniest unit is only 645 square feet, yet because it's kitted out with incredible transforming furniture, it functions like a five room apartment.

Steve Sauer, Seattle resident and Boeing aircraft interior designer, was simply looking for some storage space when he found the tiny room that would become his home. But at just 182 square feet, these DIY living quarters required a decade of work, countless hours of wrangling with city planners, and just about all…

We're running out of space, and we're running out of money—and for anyone who wants to live in a city (that's billions of humans), that's a problem. Here's a solution: micro apartments that squeeze full life into a tiny box.

Instead of creating taller buildings to cope with skyrocketing urban populations, city planners are proposing tiny "micro-apartments" of just a few hundred square feet. A measure in San Francisco proposes to create hundreds of these apartments, which could increase the population in some neighborhoods by 35 percent.…